section
  h3(id='res.attachment') res.attachment([filename])
  
  p.
    Sets the Content-Disposition header field to "attachment". If
    a <code>filename</code> is given then the Content-Type will be
    automatically set based on the extname via <code>res.type()</code>,
    and the Content-Disposition's "filename=" parameter will be set.

  +js.
    res.attachment();
    // Content-Disposition: attachment

    res.attachment('path/to/logo.png');
    // Content-Disposition: attachment; filename="logo.png"
    // Content-Type: image/png
